Hi Bill:

About the CE 2500, you might want to check what setting the O2 purge is
actaully set at with a flow meter.  The purge on this model is factory set,
and you can acess the needle valve by removing the top center cover.  I
have even increased our purge setting, and still our O2 tanks seem to last
a long time (and we still have the standard loop).

Good luck,

Bill


William  Anderson
Geologisches Institut
ETH-Zentrum
CH-8092 Zuerich
Switzerland

phone:  41-1-632-3637   lab:  41-1-632-3707             fax:  41-1-632-1080